1. Field of the Invention
The present invention relates to a mask and a method of manufacturing the mask. More particularly, the present invention relates to a mask for manufacturing a display substrate and a method of manufacturing the mask.
2. Description of the Related Art
Generally, in forming a thin-film transistor (TFT), a portion between a source electrode and a drain electrode is exposed to light by using a slit bar or a halftone layer, and then an etch-back process is performed to form a channel portion, in a method of manufacturing a display substrate using three masks or four masks.
When the channel portion is formed through an exposure process using a slit bar, a pattern caused by the diffraction of light passing through the slit is written on the photoresist, which pattern is not present in an exposure process using a halftone layer. Thus, a width of the channel portion formed in the exposure process using a slit bar is non-uniform.
On the other hand, when the channel portion is formed through an exposure process using a halftone layer, the channel portion is more uniform in comparison with the exposure process using a slit bar. However, even when using the halftone layer exposure process, the patterned channel portion is more recessed than an edge of the source electrode, to thereby incur a difference between the channel portion and the source electrode.